Ошибка при назначении события, динамически созданному StringGrid

unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Grids, StdCtrls, ExtCtrls;
 
type
  TForm1 = class(TForm)
    ScrollBox1: TScrollBox;
    procedure StGridDrawCell(Sender: TObject; ACol, ARow: Integer;
      Rect: TRect; State: TGridDrawState);
 
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
type smass = array of TStringGrid;
 
var
  Form1: TForm1;
  StGrid: smass;
  n: integer;
 
implementation
 
{$R *.dfm}
 
procedure TForm1.StGridDrawCell(Sender: TObject; ACol, ARow: Integer;
  Rect: TRect; State: TGridDrawState);
  begin
 
  end;
 
procedure Tabl(var StGrid: smass;  n: integer);
begin
SetLength(StGrid, n);
StGrid[n-1]:=TStringGrid.Create(form1.ScrollBox1);
With StGrid[n-1]  do
  begin
  Parent := form1.ScrollBox1;
  Name:='StGr'+inttostr(n-1);
  Top:=s;
  Left:=25;
  ColCount:=7;
  RowCount:=10;
  FixedCols:=0;
  FixedRows:=0;
  Width:=460;
  Height:=256;
  Font.Size:=10;
  OnDrawCell:=StGridDrawCell;  <= ОШИБКА В ЭТОЙ СТРОЧКЕ
  end;
end;
 
end.

procedure Tabl(var StGrid: smass;  n: integer; aDrawCellEvent : TDrawCellEvent);
...
begin
...
  With StGrid[n-1]  do
  begin
    ...
    OnDrawCell := aDrawCellEvent;
  end;  
...
end;

  Tabl(StGrid, n, Form1.StGridDrawCell);

...
  With StGrid[n-1]  do
  begin
    ...
    OnDrawCell := Form1.StGridDrawCell;
  end;
...